A universal gate flow calculation method under the condition of missing downstream boundary information

Abstract

The present invention discloses a general method for calculating the flow through a gate under the condition of missing downstream boundary information, including: S1, determining the gate type according to the location of the channel modeling where the gate is located; the gate includes an internal gate and a boundary gate; S2, extracting the corresponding information before and after the gate according to the gate type; S3, calculating the total head before the gate and the total head after the gate according to the extracted information before and after the gate; S4, determining the flow direction and flow state through the gate according to the relationship between the total head before the gate, the total head after the gate and the gate opening, and then calculating the flow through the gate. The method for calculating the flow through the gate provided by the present invention can effectively solve various gate boundary problems encountered in the process of water dynamic simulation of irrigation channels, especially the flow calculation under the condition of missing downstream information of the boundary gate.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrodynamic calculation, and in particular relates to a general gate flow calculation method under the condition of missing downstream boundary information. Background Art

[0002] In the process of irrigation channel hydrodynamic simulation, the gate is an important control node. The calculation of the flow through the gate directly affects the water balance and dynamic process inside the channel, and also plays a certain reference role in the gate scheduling management. The traditional method of calculating the flow through the gate requires static engineering parameters such as the gate bottom elevation, gate width, and flow coefficient, as well as dynamic parameters such as gate opening, water level before and after the gate. Generally, given the above information, the flow state through the gate is judged, and then the corresponding flow formula is used to calculate the flow through the gate.

[0003] However, during the channel hydrodynamic simulation process, the water levels before and after the gates are in dynamic change. In the case of gate scheduling, the gate opening will also change over time. Therefore, the calculation of the flow through the gate is required to be able to dynamically calculate following these changes. For the gates within the channel modeling range, the water levels before and after the gates can be extracted from the hydrodynamic simulation results in real time, and the flow through the gates is calculated and then transmitted to the hydrodynamic simulation model, thus forming a two-way feedback between the channel hydrodynamic simulation and the gate flow. However, there are certain boundaries in channel modeling, which are often divided by control nodes such as gates. The gates located at the boundaries cannot obtain water level information outside the boundaries from the hydrodynamic simulation model, resulting in the loss of information for calculating the flow through the gates. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the general method for calculating the flow through the gate under the condition of missing downstream boundary information provided by the present invention solves the problem in the existing related methods that the gate located at the boundary cannot obtain the water level information outside the boundary from the hydrodynamic simulation model, thereby causing the missing information for calculating the flow through the gate.

[0005] In order to achieve the above-mentioned invention object, the technical solution adopted by the present invention is: a general gate flow calculation method under the condition of missing downstream boundary information, comprising:

[0006] S1. Determine the gate type according to the location of the channel modeling where the gate is located; the gate includes an internal gate and a boundary gate;

[0007] S2. Extract the corresponding pre-gate and post-gate information according to the gate type;

[0008] S3, calculating the total water head before the gate and the total water head after the gate according to the extracted information before and after the gate;

[0009] S4. According to the relationship between the total water head before the gate, the total water head after the gate and the gate opening, the flow direction and flow state through the gate are determined, and then the flow rate through the gate is calculated.

[0010] Furthermore, in step S2, the extracted information before and after the gate includes the water level before the gate, the flow rate before the gate, the water level after the gate, and the flow rate after the gate;

[0011] When it is an internal gate, the information before and after the gate is directly extracted from the corresponding hydrodynamic simulation model;

[0012] The boundary gates include an inlet boundary gate and an outlet boundary gate; when it is an inlet boundary gate, the water level and flow velocity before the gate are extracted through external calculation, and the water level and flow velocity after the gate are directly extracted from the corresponding hydrodynamic simulation model; when it is an outlet gate, the water level and flow velocity before the gate are directly extracted from the corresponding hydrodynamic simulation model, and the water level and flow velocity after the gate are extracted through external calculation.

[0013] Furthermore, when it is an inlet boundary gate, the water level in front of the gate and the flow rate in front of the gate are given in the form of boundary conditions.

[0014] Furthermore, when it is an outlet boundary gate, the water level and flow rate behind the gate are extracted according to the water flow behind the gate;

[0015] When the water flow behind the gate is known or relatively stable, the water level behind the gate and the flow velocity behind the gate are given in the form of boundary conditions;

[0016] When the water flow behind the gate is unknown and there is a large drop or steep slope behind the gate, the total water head behind the gate calculated based on the water level and flow rate behind the gate is set to 0;

[0017] When the water flow conditions behind the gate are unknown and there is a conventional channel behind the gate, the empirical relationship between the water level behind the gate and the flow rate through the gate is determined based on historical monitoring data, and the water level and flow rate behind the gate are estimated.

[0018] The beneficial effect of the above further scheme is: the above method gives targeted processing measures under the condition of missing information behind the gate according to the different types of boundary gates, effectively covers various common real-life scenarios, and makes the calculation scheme closer to reality.

[0019] Furthermore, the empirical relationship between the water level behind the gate and the flow rate through the gate is a direct empirical relationship between the water level behind the gate and the flow rate through the gate or an empirical relationship between the amplitude of the water level behind the gate and the amplitude of the flow rate through the gate.

[0020] Further, according to the empirical relationship, the method for calculating the flow rate through the gate is specifically as follows: S21, calculating the preliminary flow rate through the gate according to the known water level before the gate and the flow rate before the gate, combined with the current water level after the gate and the flow rate after the gate;

[0021] S22, substituting the calculated preliminary gate flow into the empirical relationship to calculate the preliminary gate post-gate water level;

[0022] S23, calculating the preliminary flow velocity behind the gate according to the calculated preliminary flow through the gate, the preliminary water level behind the gate and the cross-sectional shape of the downstream channel;

[0023] S24, calculating an updated flow rate through the gate according to the water level before the gate, the flow rate before the gate, the preliminary water level after the gate, and the preliminary flow rate after the gate;

[0024] S25, according to the updated gate flow, based on the empirical relationship, calculate the updated water level and gate flow behind the gate;

[0025] S26, repeating steps S22 to S25 until the difference between two consecutive calculated gate flow rates is less than a given threshold, thereby obtaining the final gate-post water level and gate-post flow rate.

[0026] The beneficial effect of the above further scheme is that when both the flow rate through the gate and the water level behind the gate are unknown, the above method uses an iterative trial algorithm to determine the final flow rate through the gate and the water level behind the gate based on an implicit empirical relationship, which has higher calculation accuracy.

[0027] Furthermore, the total water head H before the gate 上 for:

[0028]

[0029] Total water head after the gate H 下 for:

[0030]

[0031] In the formula, Z 上 is the water level before the gate, Z b is the gate bottom elevation, Z 下 is the water level behind the gate, u 上 is the flow velocity before the gate, u 下 is the flow velocity after the gate, g is the acceleration of gravity; when Z 上 <Z b When H 上 =0, when Z 下 <Z b When H 下 =0.

[0032] Furthermore, the method for determining the flow rate through the gate is:

[0033] When the total water head before the gate is H 上 The total water head after the gate H 下 When they are equal, the flow through the gate is 0;

[0034] When the total water head before the gate is H 上 Greater than the total water head H after the gate下 When , the flow direction is forward flow, and the flow rate through the gate is calculated according to the flow pattern through the gate;

[0035] When the total water head before the gate is H 上 Less than the total water head H after the gate 下 When , the flow direction is reverse flow, and the flow rate through the gate calculated according to the flow pattern through the gate is taken as negative.

[0036] Furthermore, the method for calculating the flow rate through the gate according to the flow pattern through the gate is specifically as follows:

[0037] When e / H 上 ≤λ 闸 When the gate flow rate is calculated according to the gate hole flow formula:

[0038] If H 下 / H 上 ≤λ 自 , then it is free gate hole flow, the flow through the gate

[0039] If H 下 / H 上 >λ 自 , then it is the flood gate hole flow, the gate flow

[0040] When e / H 上 >λ 闸 When the flow rate through the gate is calculated according to the weir flow formula:

[0041] If H 下 / H 上 ≤λ 自 , then it is a free weir flow,

[0042] If H 下 / H 上 >λ 自 , then it is a submerged weir flow,

[0043] Where, e is the gate opening, λ 闸 is the critical coefficient between gate hole flow and weir flow, λ 自 is the critical coefficient of free flow and flooding, μ 自 is the free gate flow coefficient, μ 淹 is the flooding gate discharge coefficient, B is the gate width, m 自 is the free weir flow coefficient, m 淹 is the discharge coefficient of submerged weir flow.

[0044] The beneficial effect of the above further scheme is: the above method distinguishes four flow states according to the relationship between the total water head before and after the gate and the gate opening, and uses different empirical formulas and flow coefficients to calculate the flow rate through the gate, which effectively covers various possible scenarios and makes the method have a wider range of applications.

[0045] The beneficial effects of the present invention are:

[0046] (1) The gate flow calculation method provided by the present invention can effectively solve various gate boundary problems encountered in the process of irrigation channel hydrodynamic simulation, especially the flow calculation under the condition of missing boundary gate information.

[0047] (2) The method of the present invention provides specific treatment measures for the condition of missing information behind the gate according to different gate boundary types, effectively solving the problem of inaccurate calculation of the flow through the gate caused by missing information;

[0048] (3) The method of the present invention uses an iterative trial algorithm to process the implicit empirical relationship between the flow rate through the gate and the water level behind the gate, and the calculation result of the flow rate through the gate is more accurate;

[0049] (4) The method of the present invention comprehensively covers different flow states through the gate and has a wider application range. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 This is a flow chart of a general method for calculating gate flow under the condition of missing downstream boundary information provided by the present invention. DETAILED DESCRIPTION

[0051] The specific implementation modes of the present invention are described below so that those skilled in the art can understand the present invention. However, it should be clear that the present invention is not limited to the scope of the specific implementation modes. For those of ordinary skill in the art, as long as various changes are within the spirit and scope of the present invention as defined and determined by the attached claims, these changes are obvious, and all inventions and creations utilizing the concept of the present invention are protected.

[0052] The embodiment of the present invention provides a general method for calculating the flow rate through the gate under the condition of missing downstream boundary information, such as Figure 1 As shown, including:

[0053] S1. Determine the gate type according to the location of the channel modeling where the gate is located; the gate includes an internal gate and a boundary gate;

[0054] S2. Extract the corresponding pre-gate and post-gate information according to the gate type;

[0055] S3, calculating the total water head before the gate and the total water head after the gate according to the extracted information before and after the gate;

[0056] S4. According to the relationship between the total water head before the gate, the total water head after the gate and the gate opening, the flow direction and flow state through the gate are determined, and then the flow rate through the gate is calculated.

[0057] In step S1 of the embodiment of the present invention, the calculation of the flow rate through the gate is divided into two scenarios, based on which the types are divided. One type is the gate located inside the channel modeling, called the internal gate; the other type is the gate located at the boundary of the channel modeling, called the boundary gate; these two types of gates have different ways of obtaining information before and after the gate, and the calculation formula for the flow rate through the gate is the same.

[0058] In step S2 of the embodiment of the invention, the extracted information before and after the gate includes the water level before the gate, the flow rate before the gate, the water level after the gate, and the flow rate after the gate;

[0059] When it is an internal gate, the information before and after the gate is directly extracted from the corresponding hydrodynamic simulation model; specifically, the upstream and downstream channels of the internal gate are both within the modeling range, and the real-time information before and after the gate can be directly extracted from the hydrodynamic simulation model and substituted into the subsequent calculation formula for the flow rate through the gate.

[0060] Boundary gates include inlet boundary gates and outlet boundary gates; when it is an inlet boundary gate, the water level and flow velocity before the gate are extracted through external calculation, and the water level and flow velocity after the gate are directly extracted from the corresponding hydrodynamic simulation model; when it is an outlet gate, the water level and flow velocity before the gate are directly extracted from the corresponding hydrodynamic simulation model, and the water level and flow velocity after the gate are extracted through external calculation. Specifically, according to the characteristics of channel water supply and distribution, the inlet boundary gate is usually located at the head of the channel, and the outlet boundary gate is scattered in various control gates and water diversion gates.

[0061] In this embodiment, when it is an inlet boundary gate, the water level and flow rate before the gate are given in the form of boundary conditions. Specifically, the water flow information propagates from top to bottom, and the upstream information cannot be reversed through the downstream information. Therefore, the water level and flow rate before the gate need to be given in the form of boundary conditions. Substitute the given information before the gate and the extracted information after the gate into the gate flow formula to calculate the gate flow.

[0062] In this embodiment, when it is an outlet boundary gate, the water level and flow rate behind the gate are extracted according to the water flow behind the gate;

[0063] When the water flow conditions behind the gate are known or relatively stable, the water level and flow rate behind the gate are given in the form of boundary conditions. For example, if a reservoir is connected behind the gate, the water level is basically unaffected by the flow rate through the gate, and the flow rate can be ignored. After the flow rate and water level information behind the gate are given externally, they are combined with the extracted information before the gate and substituted into the flow rate formula to calculate the flow rate through the gate.

[0064] When the water flow conditions behind the gate are unknown and there is a large drop or steep slope behind the gate, the total water head behind the gate calculated based on the water level and flow velocity behind the gate is set to 0; specifically, when there is a large drop or steep slope behind the gate, the water level behind the gate is always lower than the gate bottom elevation. At this time, the outflow is a free gate hole flow or a free weir flow. At this time, the total water head behind the gate is set to 0. Combined with the extracted information before the gate, the flow rate through the gate is substituted into the flow formula.

[0065] When the water flow behind the gate is unknown and the gate is a conventional channel, the empirical relationship between the water level behind the gate and the flow rate after passing the gate is determined based on historical monitoring data, and the water level and flow rate behind the gate are calculated. Specifically, when the gate is a conventional channel, the water level behind the gate changes dynamically, and there is a situation where free flow and submerged flow switch. At this time, the water level behind the gate should establish an empirical relationship with the flow rate after passing the gate based on historical monitoring data, so as to calculate the water level behind the gate and then obtain the flow rate after passing the gate.

[0066] In this embodiment, the empirical relationship between the water level behind the gate and the flow through the gate is the direct empirical relationship Z(Q) between the water level behind the gate and the flow through the gate or the empirical relationship ΔZ(ΔQ) between the amplitude of the water level behind the gate and the amplitude of the flow through the gate. For the two empirical relationships, a better relationship is selected according to the measured data to calculate the water level behind the gate and the flow after the gate.

[0067] In this embodiment, based on the empirical relationship, the method for calculating the gate flow rate is specifically as follows:

[0068] S21, according to the known water level Z before the gate 上 and flow velocity u before the gate 上 , and combined with the current water level Z behind the gate 下 (0) and the flow velocity u after the gate 下 (0) , calculate the initial gate flow Q (1) ;

[0069] S22, calculate the initial gate flow Q (1) Substitute into the empirical relationship to calculate the initial water level Z behind the gate 下 (1) ;

[0070] Specifically, when the empirical relationship is Z(Q), then directly according to Q (1) Get Z 下 (1) , when the empirical relationship is ΔZ(ΔQ), then ΔQ=Q (1) -Q (0) , ΔZ=Z 下 (1) -Z 下 (0) Get Z 下 (1) ;

[0071] S23, based on the calculated initial gate flow Q (1) , Preliminary water level behind the gate Z 下 (1) and the cross-sectional shape of the downstream channel to calculate the initial flow velocity u after the gate 下 (1) ;

[0072] S24, according to the water level Z before the gate 上 , flow velocity before the gate u 上 , Preliminary water level behind the gate Z 下 (1) And the initial flow rate after the gate u 下 (1) , calculate the updated gate flow Q (2) ;

[0073] S25, according to the updated gate flow, updating the water level and the gate flow behind the gate based on the empirical relationship;

[0074] S26, repeat steps S22 to S25 until the gate flow rate Q calculated twice is (k) With Q (k+1) The difference is less than a given threshold, and the final water level and flow rate behind the gate are obtained.

[0075] In step S3 of the embodiment of the present invention, the total water head H before the gate is calculated based on the information before and after the gate extracted according to the different gate types. 上 for:

[0076]

[0077] Total water head after the gate H 下 for:

[0078]

[0079] In the formula, Z 上 is the water level before the gate, Z b is the gate bottom elevation, Z 下 is the water level behind the gate, u 上 is the flow velocity before the gate, u 下 is the flow velocity after the gate, g is the acceleration of gravity; when Z 上 <Z b When H 上 =0, when Z 下 <Z b When H 下 =0.

[0080] In step S4 of the embodiment of the present invention, the method for determining the flow rate through the gate is:

[0081] When the total water head before the gate is H 上 The total water head after the gate H 下When they are equal, the flow through the gate is 0;

[0082] When the total water head before the gate is H 上 Greater than the total water head H after the gate 下 When , the flow direction is forward flow, and the flow rate through the gate is calculated according to the flow pattern through the gate;

[0083] When the total water head before the gate is H 上 Less than the total water head H after the gate 下 When the flow direction is reverse flow, the gate flow rate calculated according to the gate flow pattern is negative. In step S4 of the embodiment of the present invention, the method for calculating the gate flow rate according to the gate flow pattern is specifically:

[0084] When e / H 上 ≤λ 闸 When the gate flow rate is calculated according to the gate hole flow formula:

[0085] If H 下 / H 上 ≤λ 自 , then it is free gate hole flow, the flow through the gate

[0086] If H 下 / H 上 >λ 自 , then it is the flood gate hole flow, the gate flow

[0087] When e / H 上 >λ 闸 When the flow rate through the gate is calculated according to the weir flow formula:

[0088] If H 下 / H 上 ≤λ 自 , then it is a free weir flow,

[0089] If H 下 / H 上 >λ 自 , then it is a submerged weir flow,

[0090] Where, e is the gate opening, λ 闸 is the critical coefficient between gate hole flow and weir flow, λ 自 is the critical coefficient of free flow and flooding, μ 自 is the free gate flow coefficient, μ 淹 is the flooding gate discharge coefficient, B is the gate width, m 自 is the free weir flow coefficient, m 淹 is the discharge coefficient of submerged weir flow.

[0091] The present invention uses specific embodiments to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

[0092] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A general method for calculating the flow rate through a gate under the condition of missing downstream boundary information, characterized in that: include: S1. Determine the gate type according to the location of the channel modeling where the gate is located; the gate includes an internal gate and a boundary gate; S2. According to the gate type, extract the corresponding information before and after the gate, including the water level before the gate, the flow rate before the gate, the water level after the gate, and the flow rate after the gate; When it is an internal gate, the information before and after the gate is directly extracted from the corresponding hydrodynamic simulation model; The boundary gates include the inlet boundary gate and the outlet boundary gate. When it is the inlet boundary gate, the water level and flow velocity before the gate are extracted by external calculation, and the water level and flow velocity after the gate are directly extracted from the corresponding hydrodynamic simulation model. When it is the outlet gate, the water level and flow velocity before the gate are directly extracted from the corresponding hydrodynamic simulation model, and the water level and flow velocity after the gate are extracted by external calculation. When it is an inlet boundary gate, the water level and flow velocity before the gate are given in the form of boundary conditions; When it is an outlet boundary gate, the water level and flow rate behind the gate are extracted according to the water flow behind the gate; When the water flow behind the gate is known or relatively stable, the water level and flow velocity behind the gate are given in the form of boundary conditions; When the water flow behind the gate is unknown and there is a large drop or steep slope behind the gate, the total water head behind the gate calculated based on the water level and flow rate behind the gate is set to 0; When the water flow behind the gate is unknown and there is a conventional channel behind the gate, the empirical relationship between the water level behind the gate and the flow through the gate is determined based on historical monitoring data, and the water level and flow rate behind the gate are estimated; The empirical relationship between the water level behind the gate and the flow through the gate is the direct empirical relationship between the water level behind the gate and the flow through the gate or the empirical relationship between the amplitude of the water level behind the gate and the amplitude of the flow through the gate; According to the empirical relationship, the method for calculating the flow rate through the gate is as follows: S21, calculating the initial flow rate through the gate based on the known water level and flow rate before the gate, combined with the current water level and flow rate after the gate; S22, substituting the calculated preliminary gate flow into the empirical relationship to calculate the preliminary gate post-gate water level; S23, calculating the preliminary flow velocity behind the gate according to the calculated preliminary flow through the gate, the preliminary water level behind the gate and the cross-sectional shape of the downstream channel; S24, calculating an updated flow rate through the gate according to the water level before the gate, the flow rate before the gate, the preliminary water level after the gate, and the preliminary flow rate after the gate; S25, according to the updated gate flow, based on the empirical relationship, calculate the updated water level and gate flow behind the gate; S26, repeating steps S22 to S25 until the difference between two consecutive calculated gate flow rates is less than a given threshold, and obtaining the final gate-post water level and gate-post flow rate; S3, calculating the total water head before the gate and the total water head after the gate according to the extracted information before and after the gate; S4. According to the relationship between the total water head before the gate, the total water head after the gate and the gate opening, the flow direction and flow state through the gate are determined, and then the flow rate through the gate is calculated.

2. The general gate flow calculation method under the condition of missing downstream boundary information according to claim 1 is characterized in that: Total water head before the gate for: Total water head after gate for: In the formula, is the water level before the gate, is the gate bottom elevation, is the water level behind the gate, is the flow velocity before the gate, is the flow velocity after the gate, is the gravitational acceleration; Z 上 < Z b hour, H 上 = 0, when Z 下 < Z b hour, H 下 = 0.

3. The general gate flow calculation method under the condition of missing downstream boundary information according to claim 2 is characterized in that: The method for determining the flow rate through the gate is: Total water head before the gate Total water head after the gate When they are equal, the flow through the gate is 0; Total water head before the gate Greater than the total water head after the gate When , the flow direction is forward flow, and the flow rate through the gate is calculated according to the flow pattern through the gate; Total water head before the gate Less than the total water head after the gate When , the flow direction is reverse flow, and the flow rate through the gate calculated according to the flow pattern through the gate is taken as negative.

4. The general gate flow calculation method under the condition of missing downstream boundary information according to claim 3 is characterized in that: The specific method for calculating the flow rate through the gate according to the flow pattern through the gate is: When e / H 上 ≤ λ 闸 When the gate flow rate is calculated according to the gate hole flow formula: If H 下 / H 上 ≤ λ 自 , then it is free gate hole flow, the flow through the gate ; If H 下 / H 上 > λ 自 , then it is the flood gate hole flow, the gate flow ; When e / H 上 > λ 闸 When the flow rate through the gate is calculated according to the weir flow formula: If H 下 / H 上 ≤ λ 自 , then it is a free weir flow, ; If H 下 / H 上 > λ 自 , then it is a submerged weir flow, ; Where, e is the gate opening, λ 闸 is the critical coefficient between gate flow and weir flow, λ 自 is the critical coefficient of free flow and flooding, is the free gate orifice discharge coefficient, is the flooding gate discharge coefficient, is the gate width, is the free weir flow coefficient, is the discharge coefficient of submerged weir flow.

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